Miniature sensor for healthcare

Engineers in the US have designed and tested tiny sensors that can be used to monitor diabetics’ glucose levels from their breath and detect possible indicators of breast cancer in saliva.

The team from the University of Florida claims early results are promising – considering that the sensor can be mass produced inexpensively with technology already widely used for making chips in mobile phones and other devices.

‘This uses known manufacturing technology that is already out there,’ said Fan Ren, a professor of chemical engineering and one of a team of engineers collaborating on the project.

The team has published 15 peer-reviewed papers on different versions of the sensor. In the most recent, the team reports integrating the sensor in a wireless system that can detect glucose in exhaled breath, then relay the findings to healthcare workers.

If fully developed, the research team is confident such a sensor could be a non-invasive replacement for the finger-prick kits widely used by diabetics.

Ren said tests with the sensor contradict long-held assumptions that glucose levels in the breath are too small for accurate assessment. That’s because the sensor uses a semiconductor that amplifies the minute signals to readable levels, he added.

‘Instead of poking your finger to get the blood, you can just breathe into it and measure the glucose in the breath condensate,’ said Ren.

The researchers also report using the sensor to detect pH levels in the breath, a technique that could help people who suffer from asthma better identify and treat asthma attacks. The engineers have used other versions to experiment with picking up indicators of breast cancer in saliva, and pathogens in water and other substances.

Ren said that tests for pH, breast or cancer indicators typically already exist, but they are often cumbersome, expensive or time consuming. For example, he added, the current technique for measuring pH in a patient’s breath requires the patient to blow into a tube for 20 minutes to collect enough condensate for a measurement.

However, it is claimed the University of Florida developed sensor, which measures only 100 microns, is so small that moisture from one breath is enough to get a pH or glucose concentration reading in less than five seconds.

Ren said the sensors work by mating different reactive substances with the semiconductor gallium nitride.

If targeting cancer, the substance is an antibody that is sensitive to certain proteins identified as indicative of cancer. If the target is glucose, the reactive molecules are composed of zinc oxide nanorods that bind with glucose enzymes.

Once the reaction happens, ‘the charge on the semiconductor devices changes, and we can detect that change,’ added Ren.

Ren admitted the sensor is not as acutely sensitive as those that rely on nanotechnology, but the manufacturing techniques are already widely available. He claimed the cost is as little as 20 cents per chip; however, this rises considerably when combined with applications to transmit the information wirelessly to computers or mobile phones. The entire wireless-chip package would start at around $40 (£25) and drop to almost half that with mass production.

The team is in the process of patenting all parts of its technology, and it claims to have already received interest from several companies looking to pursue the research.